Wizard, School of Divination Portent Feature.
After each long rest, roll two 2d20. Record the results. Then throughout the day, you can expend each result to make that be the outcome of any one attack roll, saving throw, or ability check for you or any creature you can see.
The outcome rolled by the diviner becomes the result of the targets roll. It is dependent on getting a low roll in the morning, but what isn't dependent?